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Archive - Jan 30, 2013

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First Artificial Enzyme Created by Evolution in a Test Tube

There’s a wobbly new biochemical structure in Dr. Burckhard Seelig’s lab at the University of Minnesota that may resemble what enzymes looked like billions of years ago, when life on earth began to evolve – long before they became ingredients for new and improved products, from detergents to foods and fuels. Dr. Seelig created the fledgling enzyme by using directed evolution in the laboratory. Working with colleague Dr. Gianluigi Veglia, graduate student Fa-An Chao, and other team members, Dr.Seelig subsequently determined the enzyme’s structure, which made its debut December 9 as an advance online publication in Nature Chemical Biology. Lab tests show that the enzyme (a type of RNA ligase, which connects two RNA molecules) functions as natural enzymes although its structure looks very different and it is flexible rather than rigid. Dr. Seelig speculates the new protein resembles primordial enzymes, before their current structures evolved. While a handful of groups worldwide are developing artificial enzymes, these groups use rational design to construct the proteins on computers. Instead, the Seelig lab employs directed evolution. "To my knowledge, our enzyme is the only entirely artificial enzyme created in a test tube by simply following the principles of natural selection and evolution," he says. Rational enzyme design relies on preconceived notions of what a new enzyme should look like and how it should function. In contrast, directed evolution involves producing a large quantity of candidate proteins and screening several generations to produce one with the desired function. With this approach, the outcome isn’t limited by current knowledge of enzyme structure. "Just as in nature, only the fittest survive after each successive generation," Dr. Seelig explains.

Ancient Snail Shell Analysis Reveals a Humid Mediterranean

An international team of researchers has shown that old wives' tales that snails can tell us about the weather should not be dismissed too hastily. While the story goes that if a snail climbs a plant or post, rain is coming, research led by the University of York goes one better: it shows snails can provide a wealth of information about the prevailing weather conditions thousands of years ago. The researchers, including scientists from the Scottish Universities Environmental Research Centre (SUERC), analyzed the chemistry of snail shells dating back 9,000 to 2,500 years recovered from Mediterranean caves, looking at humidity at different times in the past. Their findings, which were reported online on January 30, 2013 in the journal Quaternary International, reveal that when the first farmers arrived in Italy and Spain, the western Mediterranean was not the hot dry place it is now, but warmer, wetter, and stickier. The research was led by Dr. André Carlo Colonese from York’s Department of Archaeology. Dr. Colonese and his co-authors believe that land snails have great potential as a source of information about human behaviour and palaeoclimatic conditions and therefore should be given much more attention. Dr. Colonese, an EU Marie Curie Fellow in York’s Centre for Human Palaeoecology & Evolutionary Origins, said: “By putting together research on snails from multiple sites across Spain and Italy, we were able to produce a large-scale regional picture for weather conditions over the western Mediterranean area. This allowed us to observe differences in climate across the region.